package two;

import java.util.Scanner;

public class test11082 {
    private static int[] array = new int[25];

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt();
        System.out.println(getTreeNum(n));
    }

    private static int getTreeNum(int n) {
        if (n == 1) {
            return 1;
        }
        if (array[n] != 0) {
            return array[n];
        }

        int sum = 0;
        for (int i = 1; i < n; i++) {
            sum += getTreeNum(i) * getTreeNum(n - i);
        }
        array[n] = sum;
        return sum;
    }
}
